SAT test 8 section question 10 and 12

Hi Mike… can you solve this and explain please? Thanks!

ax + 5y = 8

12x + 15y = 10

In the given system of equations, a is a constant. If the system has no solutions, what is the value of a ?

Hi Mike, can you explain how to solve SAT 8, Section 3, #6 as a “system of equations?” Thanks.

Can you help me with Question #29 in Practice Test 3, Section 4? I found the answer by subtracting multiples of 9 from 122 to find one that was divisible by 5. Is there a better way?

Can you help with 33 in test 7 section 4?

What’s the fastest way to do test 5 #18 in the no calculator section?

Test 3 Section 3 #9 please

Test 3 Section 3 #19